Feed wheel drive mechanism for strapping tools



Nov. 8, 1966 w. J. HARADEN 3,

FEED WHEEL DRIVE MECHANISM FOR STRAPPING TOOLS 5 Sheets-Sheet 1 Filed March 31, 1965 INVENTOR:

WILLIAM J- HARADEN BY:

Nov. 8, 1966 w. J. HARADEN 3,284,049

FEED WHEEL DRIVE MECHANISM FOR STRAPPING TOOLS Filed March 51, 1965 5 Sheets-Sheet 2 FIG. 2

INVENTORl WILLIAM J. HARADEN By: EcLuJwv L G\- 80M Nov. 8, 1966 w. J. HARADEN 3,284,049

FEED WHEEL DRIVE MECHANISM FOR STRAPPING TOOLS Filed March 31, 1965 5 Sheets-Sheet 3 IO TIIH a 1A 20 6 K II 4 92 a2 2| i //%g 32 f L 38 FIG. 3 1 5 98 76 32 I] a I00 I I04 m2 74 V IIIHHL T02 FNVENTOR:

-, WILLIAM J.HARADEN United States Patent 3,284,049 FEED WHEEL DRIVE MECHANISM FOR STRAPPING TOOLS William J. Haraden, Libertyville, Ill., assignor to Signode Corporation, a corporation of Delaware Filed Mar. 31, 1965, Ser. No. 444,294 4 Claims. (Cl. 25451) The present invention relates to package binding tools by means of which a flexible metallic strap is tensioned about a package in encircling relationship, such tools commonly being referred to as strapping tools. More specifically, the invention has particular reference to a novel drive mechanism for the feed wheel which ordinarily is associated with such a strapping tool, the invention being especially concerned with portable hand operated tools wherein an intermittent manual feed is employed, utilizing the oscillatory movements of a driving pawl in association with a fixed holding pawl to periodically rotate the feed wheel and thus tension the strapping.

Heretofore, pawl-driven feed wheels associated with strapping tools invariably have employed ratchet and pawl driving mechanisms which are separate and laterally displaced from the general plane of the feed wheel and which operate in such a displaced region upon the feed wheel drive shaft to transmit their driving and holding action through the drive shaft to the feed wheel. Obviously, the use of such laterally displaced ratchet and pawl driving mechanisms has required a tool design of appreciable over-all width to accommodate the lateral or offset positioning of the ratchet wheel and its associated driving and holding pawls.

In an effort to reduce the over-all width of strapping tools of the type under consideration, it has been proposed that the driving pawl be mounted within the lateral confines of the feed wheel and that it be caused to cooperate directly with the traction teeth on the latter so that the feed wheel serves the dual function of tensioning the strapping and of eliminating the need for a separate offset ratchet wheel, as well as the outrigger frame construction ordinarily provided for supporting such separateratchet wheel. Because of the fact that any given feed wheel must, in order to maintain adequate tractional engagement wtih the strapping, of necessity be provided with a large multiplicity of small strap-engaging teeth, the design of a suitable driving pawl for such a feed wheel has presented certain problems. A single-tooth pawl soon loses its sharpness so that slipping on the feed wheel takes place and, moreover, there is a tendency for such a pawl to shear the small protuberances or teeth on the feed wheel when high strap tension is attained. Multiple teeth pawl may be more effective initially but, after a period of time when oxides and other foreign particles together with the products of strapping abrasion build up or fill the interstices of adjacent feed wheel teeth, pawl slippage will occur.

The present invention is designed to overcome the above-noted limitations that are attendant upon strapping tools which utilize a centered pawl and feed wheel construction wherein the driving pawl operates directly upon the traction teeth provided on the feed wheel and, accordingly, the invention contemplates the provision of a multiple tooth driving pawl and mounting therefor and by means of which a shifting relationship takes place between the axis of rotation of the feed wheel and the axis of oscillation of the driving pawl as it is shifted bodily during its feeding stroke and its return stroke. This shifting relationship results in a novel sliding interengagement between the mating interengaging teeth on the pawl and the feed wheel, such sliding engagement effecting a self-cleaning action whereby the interstices between adjacent teeth on the feed wheel are purged of the products of strap abrasion. In addition to this, a self-sharpening action takes place due to the fact that the sliding relationship between the mating teeth on the feed wheel and driving pawl serves to shear any burrs of rough edge deformation which may be created from time to time along an edge of a given feed wheel tooth. Still further, according to the present invention, the sliding action between the feed wheel and pawl teeth is such that a wide face-to-face contact area between at least two mating pawl and feed wheel teeth is maintained at all times during the tensioning operation despite the aforementioned shifting relationship which takes place between the axis of rotation of the feed wheel and they axis of oscillation of the driving pawl.

As will become more readily apparent as the nature of the invention is better understood, this sliding relationship between the teeth on the driving pawl and the teeth on the feed wheel is a result of the binding action which takes place on the strapping as the feed wheel shifts its position and bites deeper into the strapping as tension in the latter increases. This bodily movement of the feed wheel carries its axis of rotation further away from the axis of oscillation of the driving pawl which, unlike conventional driving pawls, has an axis of oscillation separate from the axis of rotation of the feed wheel. This allows the driving pawl to exert a progressive binding action against the feed wheel and this binding action preserves a wide mating tooth area between the feed wheel and driving pawl which does not diminish as the relationship between the position of the pawl and that of the feed wheel changes.

The novel pawl drive mechanism of the present invention is applicable to a wide variety of hand operated strapping tools and, purely for exemplary purposes it has been illustrated and described herein as being associated with a strapping tool wherein the feed wheel is raised and lowered out of and into operative engagement with the strapping by eccentric means, the feed wheel being mounted on an eccentric portion of a shaft which, when the shaft is manually rotated throughout a predetermined degree causes an orbital movement of the feed wheel involving a vertical component of shifting movement of the feed wheel to raise or lower the same, as the case may be. In the illustrated strapping tool, as well as in numerous other types of manually operable strapping tools, the direction of such orbital movement involved in releasing the feed wheel from the strapping after a given strapping tensioning operation is complete is such that unless the driving pawl is released from the feed wheel there will be an initial downward motion of the feed wheel before its upward motion becomes effective tov release the strapping and permit removal of the tool;

This downward motion is also accompanied by a forward motion of the feed wheel and the vectorial result of these two motions is one that will cause the feed wheel to bite into the strapping and weaken, rupture or otherwise damage the same. According to the present invention, when the pawl drive mechanism is applied to a strapping tool having an eccentric feed wheel control, means are provided whereby interengaging means on the pawl-operating lever or handle and on the framework or chassis of the tool or on some extraneous mechanism which may for example be associated with the motion of a seal crimping device, may be caused to become automatically effective to raise the driving pawl out of effective engagement with the feed wheel, whereupon the eccentric feed wheel disabling means may be manually actuated to raise the feed wheel from the strapping with no feed wheel binding, thus insuring easy strapping release with no damage to the strapping. i

plified construction and which therefore may be manu factured at a relatively low cost; one which is comprised of a minimum number of parts, particularly moving parts, and which therefore is unlikely to get out of order; one which is rugged and durable and which therefore will withstand rough usage; one which is capable of ease of assembly and disassembly for purposes of inspection of parts, replacement or repair thereof; one which is attractive in its appearance and pleasing in its design; and one which, otherwise is well adapted to perform the services required of it, are further desirable features which have been borne in mind in the production and development of the present invention.

Numerous other objects and advantages of the invention, not at this time enumerated, will readily suggest themselves as the nature of the invention is better understood.

In the accompanying three sheets of drawings forming apart of this specification, one illustrative embodiment of the invention has been shown.

In these drawings:

FIG. 1 is a fragmentary side elevational view of an exemplary strapping tool embodying the novel feed wheel drive mechanism of the present invention, and showing the parts in the position which they assume prior to a strapping tensioning operation;

FIG. 2 is a fragmentary sectional view taken substantially along the line 22 of FIG. 1 in the direction indicated by the arrows;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2 in the direction indicated by the arrows;

FIG. 4 is a sectional view similar to FIG. 4, showing the parts in the position which they assume during the tensioning operation;

FIG. 5 is a sectional view taken substantially along the line 55 of FIG. 2 in the direction indicated by the arrows with the parts being shown in the position which they assume immediately prior to strapping release operations;

FIG. 6 is an enlarged fragmentary exploded perspective view schematically illustrating certain feed wheel and pawl relationships employed in connection with the present invention; and

FIG. 7 is a fragmentary view of the peripheral region of the feed wheel and illustrating certain optimum shape characteristics associated with the friction surface there of.

Referring now to the drawings in detail and in particular to FIG. 1, a strapping tool embodying the improved feed wheel drive mechanism of the present invention has been designated in its entirety at 10, the tool being merely exemparly of a wide variety of strapping tools to which the present invention is capable of being applied. The particular tool selected for illustration herein is of the general type shown and described in United States patent to Crosby et al., Serial No. 2,661,030, granted on December l, 1953, and entitled, Package Binding Tool, the tool having associated therewith, in addition to the strapping tensioning mechanism, certain seal applying and crimping instrumentalities by means of which a seal may 'be withdrawn from a magazine and operatively applied to the overlapping region of the package-encircling strapping after the required degree of tension has been attained in the strapping. This disclosure of such seal applying and crimping mechanism herein is purely an incidental disclosure and bears no relation to the present invention. For a full understanding thereof, reference may be had to the above-mentioned Crosby et al. patent, the description made :herein being sufiicient merely designate or identify the disclosed parts.

Still referring to FIG. 1, briefly, the strapping tool 10 involves in its general organization a fixed main frame or chassis 12 and an auxiliary oscillatable frame 14. The

main frame 12 serves to support thereon the major portion of a strapping-tensioning mechanism including a feed wheel 16, while the auxilliary frame 14 serves to support thereon a seal magazine 18, a seal crimping mechanism 20 including crimping jaws 21, and a seal feeding mechanism 22 by means of which seals may be fed from the seal magazine 18 to the seal crimping mechanism 20. An

operating handle or lever 24 is pivotally mounted on the auxilliary frame 14 by means of a pivot pin 25 and is adapted to be oscillated within a first range of movement during which the auxiliary frame moves bodily with it for actuating the tensioning mechanism, after which the handle 24 may be swung through a second range of movement to bring the sealing mechanism, together 'with a pre-positioned seal which previously has been fed thereto, into operative register with the overlapping ends of the tensioned strapping. Finally, the handle 24 may be swung or forced through a third range of movement while auxiliary frame 14 remains stationary to cause the sealing mechanism to be actuated to crimp the seal about the overlapping portions of the tensioned strapping to form a joint and unite the overlapping portions, thus creating a tensioned loop or strap about the package undergoing strapping. Finally, the handle 24 is returned to its initial position within the first range of swinging movement, during which time a new seal is fed to the sealing mechanism while the auxiliary frame 14 is restored to its normal position.

The manner in which the handle 24 is effective in the second range to attain register of the sealing mechanism with the overlapping ends of the strapping, and the manner in which it is effective in the third range to seal such overlapping ends constitutes no part of the present invention which is directed principally to the nature of the strapping tensioning means and the manner in which the handle 24 is effective in the first range of move ment to effect such tensioning. However, and as will be pointed out in greater detail presently, novel means are provided according to the present invention for disabling a portion of the strapping tensioning means at such time as the handle 24 leaves the first range of movement and enters the second range to the end that, during return of the handle to the first range of movement, binding of the feed wheel 16 against the strapping will be precluded and release of the tool from the strapping Will be facilitated Without damage to the strapping.

The main frame or chassis 12 may be in the form of a lightweight aluminum alloy casting and it is formed with a flat bottom surface 30 which is adapted to rest upon the package undergoing strapping. As best seen in FIG. 2, this main frame or chassis is generally of L-shape de- 1 sign in transverse cross section and includes a vertical supporting Wall 32 from the lower regions of which there projects laterally a horizontal foot or base 34. An elongated narrow extension 36 is integrally formed with the- 'base 34, extends rearwardly therefrom, and merges with an arched portion 38 which overlies the extension and, in turn, merges with the supporting wall 32 at its forward end region and along one edge region thereof. The arched portion 38 and the extension 36 which it overlies, are thus offset slightly from the general plane of the vertical wall 32 and are aligned longitudinally with the base 34. The extension 36 and arched portion 38 constitute, in effect, an integral handle which may be employed for transporting the strapping tool. The forward end of the arched portion 38 is bifurcated, one leg of the bifurcation comprising the wall 32 (FIG. 4) and the other leg being in the form of a forward projecting flange or car 40 (FIGS,

1, 2 and 5) which is spaced laterally from the wall 32.-

The auxiliary frame 14 projects into the rec ess which exists between the wall 32 and car 40 and is pivoted for swinging movement on the main frame 12 by means of a transverse shaft 42 which traverses the recess and is rotatwhich the feed wheel 16 is rotatably mounted and with a reduced end region 45. The shaft 42 is capable of limited manual turning movement through an angle of approximately 90 to the end that orbital movement of the eccentric portion 44 may serve to lower and raise the feed wheel bodily toward and away from the strapping.

As best seen in FIGS. 1 and 6, turning movement of the shaft 42 is effected under the control of a handle 50 carried on a crank arm 52, the latter being secured by a stud bolt 54 to an end of the shaft 42 and having an interlocking ear and slot connection 56 with the shaft. A spring housing assembly 57 is secured by a nut 58 to the reduced end region 45 of the shaft 42 remote from the handle '50 and serves yieldingly to bias the shaft in a counterclockwise direction as viewed in FIG. 1 and normally lower the feed wheel 16 into operative feeding engagement with the strapping. The assembly includes a spring 59 (see also FIG. 2), one 'end of which is anchored in the wall 32 and the other end of which is anchored in a collar 60 which is keyed to the reduced end region 45 of the shaft 42. Releasable spring pressed latch means in the form of a latching lever 61, pivoted on a pin 62, and capable of latching engagement with a latch pin 64 on the crank arm 52, is provided for the purpose of maintaining the feed wheel 16 in an elevated position out of contact with the strapping for releasing the tool from the strapping after a given package binding operation has been completed.

As shown in FIGS. 3, 4 and 5, the laterally extending horizontal foot or base 34 is formed with a relatively large opening 70 therein into which the outer end of the seal crimping mechanism 20 projects when the latter is moved to joint-forming position over the overlapping ends of the package-encircling strapping. A removable and replaceable anvil 27 in the form of a hardened steel plug having a knurled upper surface is threadedly received in the foot 34 and underlies the feed wheel 16 for cooperation with the latter in the usual manner during strapping tensi-oning. In the normal use of the strapping tool 10, the strapping is looped around the package undergoing binding and the tool is positioned on the pack-age by sliding the foot 34 laterally beneath the overlapping ends of the binder loop so that the anvil 72 underlies these ends while the feed wheel 16 overlies the same. Ordinarily the tool is so positioned that the free end portion 74 of the strapping S will immediately overlie the anvil 72 and extend rearwardly or to the right as seen in FIGS. 3, 4 and 5, while the unsevered and movable feed end portion 76 of the binder loop will overlie the end region 74 and immediately underlie the feed wheel 16 for movement to the left during the tensioning operation. During such tensioning operation, the downward pressure of the feed wheel against the overlapping end portions 74 and 76 of the binder loop will cause the free end portion 74 to be held stationary on the anvil 72 while the unsevered feed end portion 76 will slide upon the free end portion 74 in the usual manner as the feed wheel 16 is intermittently rotated in a clockwise direction under the control of the oscillatable handle 24 when the latter is oscillated in the first range of movement as previously set forth, the handle operating through the media of the ratchet and pawl drive mechanism of the present invention to effect intermittent strapping tensioning operations as will be described presently.

The arrangement of parts thus far described is purely conventional, the nature and operation of such parts being more fully set forth in 'the above-mentioned patent to Crosby et al., -No. 2,661,030, and no claim is made herein to any novelty associated therewith. The novelty of the present invention consists rather in the construction, combination and arrangement of parts which constitute the feed wheel drive mechanism for intermittently advancing the feed wheel 16 during strapping tensioning operations and for releasing the feed wheel from the tensioned strapping after the seal crimping mechanism 20 has placed a seal upon the overlapping end regions of the binder loop and crimped the same in position thereon. Such feed wheel drive mechanism will now be fully described and subsequently claimed.

Referring to FIG. 2, the auxiliary frame 14 is provided with a depending bifurcated saddle portion 80 including spaced apart saddle legs or flanges 82, one flange being mounted for rocking movement on the main body portion of the shaft 42 and the other flange being similarly mounted for rocking movement on the reduced end region 45 of the shaft by means of an interposed sleeve or bushing 84. The shaft 42 thus constitutes a pivot shaft for the entire auxiliary frame 14, as well as an eccentric shaft for the feed wheel mounting.

As best seen in FIGS. 3 to 6 inclusive, a pin extends between the two flanges 82 of the auxiliary frame 14 and serves to support thereon a feed wheel driving pawl 92 which is yieldingly urged by a spring 94 into driving cooperation with the fee-d wheel 16, one end of the spring bearing against an underneath surface of the frame 14 and the other end thereof bearing against a shoulder 96 on the pawl. The auxiliary frame 14 and its operating handle 24, when considered as a unit and apart from the seal magazine 18, the seal crimping mechanism 20, and the seal feeding mechanism 22, constitutes, in effect, a pawl-carrying strap-tensioning lever which is capable of oscillatory movements on the main frame for straptensioning purposes in the usual manner of feed wheel advancement. The main frame 12 is provided with a forwardly facing recess 98 immediately in front of the arched portion 38. A pin 100 projects across the recess 98 and pivotally supports thereon a holding pawl 102 which is yieldingly urged into holding cooperation with the feed wheel 16 by a spring 104. The spring bears at one end against the rim region of the recess 98 and at its other end against a shoulder 106 on the pawl 102.

The present invention is predicated largely upon the fact that both the driving pawl 92 and the holding pawl 102 cooperate with the feed wheel 16 by direct contact with the peripheral strap-engaging teeth thereon instead of with a separate ratchet wheel which is laterally displaced from the feed wheel as is invariably the case with conventional intermittently operated pawl-actuated feed wheels. As previously stated, satisfactory fee-d wheel design requires that the periphery of a feed wheel shall present a relatively large area of contact to the strapping undergoing tensioning and that such area shall have an extremely high coeflicient of friction with respect to the strapping so that slippage will not occur. To attain this high frictional characteristic, it has been customary to employ a large multiplicity of small closely spaced pointed protuberances on the periphery of the feed wheel. The radial extent or height of these protuberances must not be too great lest the strapping become punctured or otherwise weakened or deformed but a small amount of penetration is permissible. As a general rule, the traction protuberances may be of such radial extent that they conform to the elastic limit of the steel from which the strapping is made and that they do not depress the material of the strapping appreciably beyond its ability to resume its original planar condition after the feed wheel has traversed the same. It is obvious then that peripheral traction protuberances of such small magnitude are not readily compatible with conventional driving pawls, especially single tooth driving pawls which would normally tend to shear the protuberances from the perpiheral face of the feed wheel under the high tensional loads normally encountered in connection with strapping tools of the character under consideration. The same holds true in the case of conventional holding pawls.

In the illustrated form of the invention, a novel feed wheel surface configuration and a cooperating driving and holding pawl surface configuration are employed which are entirely compatible with one another, the peripheral surface configuration of the feed wheel possessing adequate tractional or gripping characteristics to drive the strapping for tensioning purposes, and the cooperating surfaces of the driving and holding pawls being such that they offer sufiicient gripping contact to the feed wheel that there will be no feed wheel slippage, either during driving by the driving pawl or holding by the holding pawl. Such surface configurations are best illustrated in FIGS. 3 and 6 but they represent merely optimum surface configurations and the invention is not to be limited to their use exclusively since other configurations may eitectively be employed. In its broadest aspect, the invent-ion contemplates the use of a feed wheel having a large multipli-city of traction protuberances thereon and cooperating driving and holding pawls having surfaces which, themselves, make adequate gripping contact with the feed wheel to drive or hold the same under the extremely high tensional forces which frequently are involved in connect-ion with strapping tools of the character under consideration.

As best seen in FIGS. 6 and 7, the periphery of the feed whee-l 16 is formed with a large multiplicity of closely spaced protuberances or teeth 110 which may be formed by milling a series of transversely extending circumferentially spaced V-grooves 112 in the periphery of the wheel and then milling the wheel in a circumferential direction along laterally spaced regions to relieve the transversely extending ribs which are formed in the first milling operation as indicated at 114 in FIG. 7, thus providing the individual protuberances 110. These protuberanoes are arranged in transverse rows of five teeth each and they also are arranged in five circular rows. The individual protuberances 110 being generally pyramidal but, instead of having pointed apices, the crest portions 116 of the protuberances are of sharp knife-like linear extent. These protuberances 110 are designed for sliding cooperation with mating protuberances 118 on the driving pawl and similar protuberances 120 on the holding pawl 102.

The protuberances 118 and 120 are similar in their design and are in the form of V-shaped ribs which are spaced apart a distance substantially commensurate with the spacing of the transverse rows of protuberances 110 on the feed .wheel 16. The slope angles maintained in constructing the diverging sides of the protuberances 118 and 120 are commensurate with the slope angles maintained in constructing the diverging sides of the protuberances 110 so that when the pawls 92 and 102 are in effective engagement with the feed wheel 16, cooperating protuberances on the pawls and feed wheel will make substantially coextensive face-to-face contact with one another along the sides of the protuberances. Each mating protuberance or rib on either pawl 92 or 102 will thus engage five of the protuberances on the feed wheel 16. In addition to the maintenance of equal slope angles as set forth above, the spacing of protuberances on the pawls and feed wheel and the magnitude of the approach or energizing angles maintained between the pawls and the feed wheel as previously defined, is such that no less than two protuberances on each pawl is at all times, during the tensioning operation upon the strapping, in contact with their respective groups of five protuberances on the feed wheel 16. The terms approach angle and energizing angle as employed herein relates to the binding action which takes place between the driving pawl and the fee-d wheel during the strap tensioning operation. This angle may be defined as the angle subtended by the longitudinal axis of the driving pawl and an axis passing through the pivot pin for the pawl and the rotational axis of the feed wheel.

It has previously been set forth how the operating handle 24 is oscillatable in a first range of movement to effect swinging movement of the auxiliary frame 14 within this range for strapping tensioning purposes, is

movable through a second range of movement to bring the sealing mechanism 20 and a seal carried thereby into operative register with the overlapping ends 74, 76 of the tensioned strapping, and is movable in a third range to efiiect seal crimping operations. Since the present invention is concerned solely with strapping tensioning operations, the operation of the strapping tool 10 will be described only with respect to the movements of the operating handle 24 in the first range.

Assuming that the strapping S has been looped about a package, and that by lateral movement of the tool or of the overlapping portions of the strapping such ends have been caused to underlie the feed wheel 16 and overlie the anvil 72, the operator will then cause the latching lever 61 to be swung in a clockwise direction as viewed in FIG. 1, thus releasing the crank arm 52 and shaft 42 for counter-clockwise movement under the influence of the spring 57 associated with the spring housing assembly 57. Such rotation of the shaft 42 lowers the feed wheel 16 into frictional contact with the upper overlapping feed portion 76 of the strapping and presses the lower feed portion 74 into frictional contact with the anvil 72. The tool 10 is then in condition to tension the strapping and this is accomplished by oscillating the operating handle 24 in its first range of movement to thus also oscillate the auxiliary frame 14 which carries the driving pawl 92. Oscillation of the auxiliaryframe 14 in the first range serves to cause oscillation of the driving pawl in the usual manner of driving pawl movement, each clockwise stroke of the pawl serving to impart an increment of rotation to the feed wheel for strap tensioning purposes. The degree of tension progressively attained during each operative stroke of the driving pawl 92 is retained by the action of the holding pawl 102 during the return stroke of the driving pawl. During these operations the magazine 18 and sealing mechanism 20 oscillate bodily with the auxiliary frame 14 but perform no functions.

It is to be observed at this point, and by an inspection of FIGS. 2 and 4, that a relatively small approach or energizing angle is maintained by the pawl 92 with respect to the feed wheel, this energizing angle having previously been defined and being designated in FIG. 4 at 0. While the magnitude of this angle may be varied within certain limits, it has been found that an energizing angle on the order of 10 will aiford optimum binding action of the pawls against the feed wheel under all normal conditions of strap tensioning.

It is to be noted that because the feed wheel 16 is mounted on an eccentric portion 44 of the shaft 42, it has a similar self-energizing action with respect to the strapping undergoing tensioning. The greater the tension in the strapping, the more closely will it approach the anvil 72 and the more deeply will it be drawn into the strapping. This progressive shifting movement of the axis of the feed wheel will lengthen the distance between the axis of the feed wheel and the curved path of oscillation of the driving pawl 92, thus decreasing the energizing angle 0 and changing the relationship between the mating teeth on the feed wheel and the driving pawl. These teeth will thus slide to new relative positions with respect to each other.

It is also to be noted at this point that the relatively sharp shape-characteristics of the teeth on the pawls 92 and 102 and the V-groove configuration of the teeth on the feed wheel 16 are conducive toward a self-cleaning action that is lacking in connection with the spur gearing tooth design employed in connection with conventional ratchet and pawl devices. By the present tooth design, metal particles, oxides and other foreign substances which invariably accumulate on the surface of conventional feed wheels are swept clean from the peripheral surface of the present feed wheel by a wiping action which takes place as the various protuberances involved move into and out of mating register with one another. By the same token a self-sharpening action is effected and any burrs which may tend to accumulate on the crests of any of the friction protuberances involved are removed by a simulated honing action as the various mating protuberances sweep past one another.

When the desired tension in the strapping is attained, the operating handle 24 is swung in a counterclockwise direction as viewed in FIG. 1 to the position which it assumes in FIG. 5 wherein it is at its upper limit in the first range of movement. Abutting shoulders on the auxiliary frame 14 and main frame 12 then move into engagement to limit the counterclockwise movement of the auxiliary frame 14 and the crimping jaws 21 together with their supported seal move into register with the overlapping end regions 74 and 76 of the strap-ping S. Further movement of the operating handle 24 through the second and third range of movement leaves the auxiliary frame in its tilted position while the handle swings about the axis of the pivot pin 25 and initiates the seal crimping operation :as fully described in the above-mentioned patent to Crosby et al., No. 2,661,030.

To release the tool from the tensioned strapping, the handle 24 is swung from its extreme posit-ion in the third range of movement in a clockwise direction as viewed in FIG. 1 back into the first rangeof movement and, prior to its arrival in this latter range, a fresh seal is projected from the magazine 18 and into operative position within the seal crimping mechanism 20 in the manner likewise set forth in the above-mentioned patent to Crosby et al. The handle 50 and its associated crank arm 52 (FIG. 1) is then rotated in a clockwise direction until the latch pin 64 is effective to maintain the crank arm latched in the position in which it is illustrated in this view. Such rotation of the crank arm 52 causes the shaft 42 (FIG. 6) to be rotated throughout a predetermined angle to raise the eccentrically mounted feed wheel 16 from the strapping so that the parts assume the positions in which they are shown [in FIG. 3.

It should be observed that upon initial movement of the crank arm 52 toward its position of feed wheel release from the strapping a small component of downward motion accompanied by a relatively large component of horizontal motion toward the left as viewed in 'FIG. 5 is applied bodily to the feed wheel 16. This component of downward motion is of short duration and lasts only until such time as the feed wheel has passed over a dead center position, so to speak, wherein the downward pressure upon the strapping is at a maximum because the periphery of the feed wheel is at its extreme limit of proximity to the anvil 72. Immediately after the feed wheel 16 has passed this dead center position, its component of horizontal movement is largely horizontal and, as the crank arm 52 continues to be rotated, the horizontal component of bodily motion of the feed wheel rapidly diminishes in favor of a vertical component of movement, the ratio of vertical movement to horizontal movement changing according to a function of the sine of the angle involved as the feed wheel swings outwardly and upwardly away from a vertical plane. Since the teeth on the feed wheel are in tight frictional contact with the fully tensioned strapping S which cannot yield in either direction because the seal has been applied thereto, it is necessary to release the driving pawl 92 from the feed wheel 16 to avoid binding of the feed wheel between the unyielding driving pawl and the unyielding strapping. Otherwise there would be a tendency for the feed wheel to tear the strapping during its initial bodily movement when the crank arm 52 is first moved toward its position of feed wheel release. Accordingly, the driving pawl is provided with a laterally projecting pin 122 thereon which is designed for engagement with a fixed trip pin 124 (FIGS. 1 and 5) which projects upwardly from the upper surface of the flange 40 on the main frame 12 and is positioned in the path of movement of the pin 122. At such time as the operating lever 24 moves to its upper limit in the first range of movement, the pin 122 engages the fixed trip pin and, by a camming action thereagainst, causes the driving pawl 92 to be lifted clear of the feed wheel as clearly shown in FIG. 5. The feed wheel 16 is thus freed from the influence of the pawl 92 and since it makes firm tractional engagement with the strapping S, and moreover since it is not bound by the holding pawl 102, the component of bodily shifting movement imparted to it by initial movement of the crank arm leaves the feed wheel free to roll on the strapping and thus turn in a clockwise direction past its dead center position and to its fully raised position. The tool 10 may then be removed from the bound package by sliding the same laterally until the foot or base portion 34 of the main frame 12 slides from beneath the tensioned and sealed loop of strapping.

The particular release mechanism for the driving pawl 92 and embodying the cooperating pins 122 and 124 represents a preferred automatic means for effecting release of the feed wheel by the driving pawl so that there will be no binding of the feed wheel between the pawl and the strapping when the shaft 42 is rotated to raise the feed wheel from the strapping. Other release means, whether automatic or manual are contemplated. For example, instead of relying upon the auxiliary frame 14 to swing the driving pawl 92 to a position wherein the pin 122 on the driving pawl engages a member on the main frame for tripping the driving pawl and raising it out of contact with the feed wheel 16, the driving pawl may be tripped by engagement thereof with some moving part of the seal feeding mechanism, the seal crimping mechanism, or any other independently operable instrumentality which may be associated with the strapping tool. Where manually operable strapping tools which do not employ built-in seal feeding or seal crimping mechanisms are concerned, the trip pin 124 may be omitted and the pin 122 may be made readily accessible to the operator for manual lifting of the driving pawl 92 from contact with the feed wheel 16.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.

Having thus described the invention, what I claim and desire to secure by Letters Patent is:

1. In a package strapping tool for tensioning a loop of strapping about an article, said loop having overlapping free end and feed end portions, a frame adapted to rest upon the article and having an anvil surface adapted to underlie said overlapping end portions, a rotatable strap-tensioning feed wheel mounted on said frame for swinging movement about a first horizontal axis bodily toward and away from the anvil surface into and out of strap-engaging position, said feed wheel being provided with a series of peripheral teeth thereon engageable with the feed end portion of the strapping for strap tensioning purposes when the feed wheel is rotated in a tensioning direction, a strap tensioning lever pivoted to said main frame for oscillatory rocking movement about a second horizontal axis displaced from said first horizontal axis, a driving pawl pivotally mounted on said lever and having a series of teeth thereon directly engageable with teeth on the feed wheel for applying driving torque to the feed wheel when the tensioning lever is rocked in a tensioning direction, spring means normally urging the pawl into cooperating engagement with the feed wheel the combined effective length of the driving pawl and effective diameter of the feed wheel being slightly greater than the distance between the axis of rotation of the feed wheel and the pivotal axis of the pawl whereby in any position of the feed wheel a self-energizing binding action of the teeth on the pawl against the teeth on the feed wheel with consequent relative sliding tooth engagement will take place when the lever is rocked in a tensioning direction, and a holding pawl pivotally mounted on the main frame and also having teeth thereon on each of said pawls is substantially equal to the effective width of the teeth on the feed wheel.

3. In a package strapping tool, the combination set forth in claim 1 and including, additionally, interengaging means on said driving pawl and main frame for moving said driving pawl out of operative engagement with the feed wheel against the action of said spring means when said lever approaches the limit of its movement in its reverse direction.

4. In a package strapping tool, the combination set forth in claim 3, wherein said interengaging means on the pawl and main frame comprises a laterally projecting pin on said driving pawl, and an upstanding pin on said main frame and positioned in the path of movement of said laterally projecting pin and designed for camming engagement therewith during movement of said lever in its reverse direction.

References Cited by the Examiner UNITED STATES PATENTS 2,072,566 3/ 1937 Pervelet 254-5 1 2,151,417 3/1939 Blount.

2,156,062 4/ 1939 Porter 254-51 2,229,522 1/ 1941 Porter 254-51 2,430,480 11/1947 Pugh 7457 8 X 2,569,623 10/1951 Wognum 25451 2,661,030 12/1953 Crosby et a1. 140-93.!- 2,986,376 5/1961 Falck-Pedersen 25479 WILLIAM FELDMAN, Primary Examiner.

2O MILTON S. MEHR, Examiner. 

1. IN A PACKAGE STRAPPING TOOL FOR TENSIONING A LOOP OF STRAPPING ABOUT AN ARTICLE, SAID LOOP HAVING OVERLAPPING FREE END AND FEED END PORTIONS, A FRAME ADAPTED TO REST UPON THE ARTICLE AND HAVING AN ANVIL SURFACE ADAPTED TO UNDERLIE SAID OVERLAPPING END PORTIONS, A ROTATABLE STRAP-TENSIONING FEED WHEEL MOUNTED ON SAID FRAME FOR SWINGING MOVEMENT ABOUT A FIRST HORIZONTAL AXIS BODILY TOWARD AND AWAY FROM THE ANVIL SURFACE INTO AND OUT OF STRAP-ENGAGING POSITION, SAID FEED WHEEL BEING PROVIDED WITH A SERIES OF PERIPHERAL TEETH THEREON ENGAGEABLE WITH THE FEED END PORTION OF THE STRAPPING FOR STRAP TENSIONING PURPOSES WHEN THE FEED WHEEL IS ROTATED IN A TENSIONING DIRECTION, A STRAP TENSIONING LEVER PIVOTED TO SAID MAIN FRAME FOR OSCILLATORY ROCKING MOVEMENT ABOUT A SECOND HORIZONTAL AXIS DISPLACED FROM SAID FIRST HORIZONTAL AXIS, A DRIVING PAWL PIVOTALLY MOUNTED ON SAID LEVER AND HAVING A SERIES OF TEETH THEREON DIRECTLY ENGAGEABLE WITH TEETH ON THE FEED WHEEL FOR APPLYING DRIVING TORQUE TO THE FEED WHEEL WHEN THE TENSIONING LEVER IS ROCKED IN A TENSIONING DIRECTION, SPRING MEANS NORMALLY URGING THE PAWL INTO COOPERATING ENGAGEMENT WITH THE FEED WHEEL THE COMBINED EFFECTIVE LENGTH OF THE DRIVING PAWL AND EFFECTIVE DIAMETER OF THE FEED WHEEL BEING SLIGHTLY GREATER THAN THE DISTANCE BETWEEN THE AXIS OF ROTATION OF THE FEED WHEEL AND THE PIVOTAL AXIS OF THE PAWL 